研究概述
Towards multi-scale topology optimisation of heat exchangers (MSCA Postdoc Project)
Microchannel cooling is often the preferred choice for compact heat sinks. However, widely adopted topology optimisation (TO) techniques, such as density-based and level-set methods, often struggle to generate very thin channel strips without imposing maximum length scale constraints. To address this limitation, multi-scale design methodologies have emerged. This paper builds upon recent advances in de-homogenisation techniques to contribute to the multi-scale design of microchannels for cooling applications. We start by selecting a single-class microstructure and employ numerical homogenisation to build an offline library. This library is then fed in online macro-scale topology optimisation, where both microstructure parameters and local orientation fields are optimised. By using a sawtooth-function-based mapping, the de-homogenised results capture fine details across different length scales through a unique homogenised design. Our findings show that the generated microchannels outperform conventional pillar arrays, offering valuable insights for heat sink designers. Additionally, imperfections observed in the de-homogenised results serve as benchmarks for future improvements, addressing concerns related to modelling accuracy, manufacturability, and overall performance enhancements.
Hao Li, Pierre Jolivet, and Joe Alexandersen, Multi-scale topology optimisation of microchannel cooling using a homogenisation-based method. Preprint submitted to Structural and Multidisciplinary Optimization. [Preprint]
Turbulent flow modelling and optimisation (PhD Candidate: Amirhossein Bayat)
PhD Candidate: Amirhossein Bayat; Supervisor: Joe Alexandersen; Co-supervisor: Hao Li
This project focuses on advancing the understanding and control of turbulent flows, which are prevalent in various engineering applications such as aerospace, automotive, and energy systems. This research aims to develop and refine computational models to accurately simulate turbulent flows, capturing the complex interactions and chaotic nature inherent to these phenomena. Additionally, the project explores optimisation techniques to enhance the efficiency and performance of systems involving turbulent flows. By integrating advanced numerical methods and high-performance computing, this work seeks to contribute to the design of more efficient and sustainable engineering solutions.
An easy-to-use and parallel framework for density-based topology optimization
Conjugate heat transfer in heat exchangers is at the heart of numerous industrial applications. Topology optimization (TO) is a promising numerical method that allows for the design of high-performance thermo-hydraulic systems from scratch. However, full-scale three-dimensional thermofluidic TO remains largely within the academic sphere and has yet to be easily explored by thermal engineers. To bridge this gap, this paper presents an integrated design workflow tailored for three-dimensional, high-resolution topology optimization of conjugate heat transfer systems, incorporating a mean compliance constraint to ensure structural integrity and load-bearing capability. This is achieved using a dual-mesh approach within the density-based TO framework. We also introduce Tanatloc, a user-friendly graphical user interface developed in JavaScript, which provides versatile functionalities and an interactive experience for thermal engineers. Finally, a 3D printed metal-based prototype is fabricated, and reverse engineering is conducted to reconstruct a CAD model using CT-scan images, paving the way for future experimental investigations.
A single-phase fluid heat exchanger design. (We acknowledge the financial support from DENSO CORPORATION, Japan)
*An industrial application paper is under preparation.
Level set-based topology optimization of thermal fluid-structure systems (PhD project)
This thesis focuses on topology optimization (TO) of thermal fluid-structure systems motivated by aeronautic and thermal management industrial applications. Topological design sensitivity of arbitrary cost functionals is derived for a weakly coupled thermal fluid-structure model. A reaction-diffusion equation-based level-set method is then developed for solving generic constrained topology optimization problems with which one can design from scratch, that is, new holes (resp. islands) can be nucleated during topological evolution. Motivated by the need for real-world applications, two key ingredients are introduced into this workflow. The first is the physics-tailored multigrid preconditioner for distributed finite element analysis. This ensures that the physical computation part of the TO framework can be highly scalable with respect to the problem size. The second is the two different unstructured mesh adaptation techniques. More specifically, body-fitted meshes, as one of the surface capturing techniques, allows the disjoint-reunion of a global mesh that involves several (fluid/solid) subdomains. Anisotropic meshes fit high aspect ratio elements (highly stretched elements) along the regions of rapid variation of the solutions like interior or boundary layers. All these ingredients allowed us to solve a variety of two- and three-dimensional multiphysics test cases, from single physics problems in 2D to coupled physics in large-scale 3D settings including minimal mean compliance, minimal power dissipation, design-dependent and design independent-fluid-structure interaction (FSI), natural/forced convection, lift--drag problems. The final opening chapter sheds a light on lattice design. Motivated by the need for porous structure in the design of biodegradable implants, a variational method (PDE-filter) is used in order to simplify the numerical evaluation of geometric constraints: it enables to computing “local averaged” characteristic function on an unstructured mesh by solving this PDE without requiring the neighbourhood element spatial information.
Hao Li, Takayuki Yamada, Pierre Jolivet, Kozo Furuta, Tsuguo Kondoh, Kazuhiro Izui, and Shinji Nishiwaki. "Full-scale 3D structural topology optimization using adaptive mesh refinement based on level-set method." Finite Elements in Analysis and Design 194 (2021): 103561, DOI: 10.1016/j.finel.2021.103561.
Hao Li, Tsuguo Kondoh, Pierre Jolivet, Kozo Furuta, Takayuki Yamada, Benliang Zhu, Kazuhiro Izui, and Shinji Nishiwaki."Three-dimensional topology optimization of fluid-structure system using body-fitted mesh adaption based on the level-set method." Applied Mathematical Modelling 101 (2022): 276-308, DOI: 10.1016/j.apm.2021.08.021.
Hao Li, Tsuguo Kondoh, Pierre Jolivet, Kozo Furuta, Takayuki Yamada, Benliang Zhu, Heng Zhang, Kazuhiro Izui, and Shinji Nishiwaki."Optimum design and thermal modeling for 2D and 3D natural convection problems incorporating level set-based topology optimization with body-fitted mesh." International Journal for Numerical Methods in Engineering 123, no. 9 (2022): 1954-1990, DOI: 10.1002/nme.6923.
Hao Li, Tsuguo Kondoh, Pierre Jolivet, Nari Nakayama, Kozo Furuta, Heng Zhang, Bengliang Zhu, Kazuhiro Izui, and Shinji Nishiwaki."Topology optimization for lift-drag problems incorporated with distributed unstructured mesh adaptation." Structural and Multidisciplinary Optimization 65 (2022): 1-15, DOI: 10.1007/s00158-022-03314-w.
Hao Li, Minghao Yu, Pierre Jolivet, Joe Alexandersen, Tsuguo Kondoh, Tiannan Hu, Kozo Furuta, Kazuhiro Izui, and Shinji Nishiwaki. "Reaction-diffusion equation driven topology optimization of high-resolution and feature-rich structures using unstructured meshes." Advances in Engineering Software 108 (2023): 103457, DOI: 10.1016/j.advengsoft.2023.103457.
Experimental and numerical investigation of high heat flux heat sink designed by topology optimization (Master project)
From the engineering point of view, we experimentally and numerically investigated the relationship between the liquid-cooled channel layout designed by topology optimization and the flow and thermal performances. Our research can be applied to the thermal management of microprocessors, electric vehicle batteries, LED displays, etc.
Hao Li, Xiaohong Ding, Fanzhen Meng, Dalei Jing, and Min Xiong. "Optimal design and thermal modelling for liquid-cooled heat sink based on multi-objective topology optimization: An experimental and numerical study." International Journal of Heat and Mass Transfer 144 (2019): 118638, DOI: 10.1016/j.ijheatmasstransfer.2019.118638.
Hao Li, Xiaohong Ding, Dalei Jing, Min Xiong, and Fanzhen Meng. "Experimental and numerical investigation of liquid-cooled heat sinks designed by topology optimization." International Journal of Thermal Sciences 146 (2019): 106065, DOI: 10.1016/j.ijthermalsci.2019.106065.